Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

444
FXUS63 KLOT 291723
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1223 PM CDT Wed Apr 29 2026

.KEY MESSAGES...

- The next few days will be characterized by relatively cool
  temperatures, afternoon showers, and chilly nights.

- Patchy frost may develop the next few nights with a
  widespread frost Friday night into Saturday morning

- Slightly warmer, but also wetter, conditions may arrive by
  this weekend.

&&

.DISCUSSION...
Issued at 123 AM CDT Wed Apr 29 2026

Upper-level troughing with embedded shortwaves now encompasses
much of the northern United States. With little in the way of
change in the upper-level pattern through the next 48 hours,
today and Thursday will be more or less the same with seasonably
cool temperatures and diurnally-driven isolated to scattered
showers. Highs today and tomorrow will reach the upper 50s to
lower 60s, except the upper 40s to lower 50s lakeside due to
lake breezes. Each afternoon will not be a washout, though
isolated to scattered showers (perhaps with embedded graupel)
will move through the area during peak heating. Finally,
overnight lows will fall into the mid to upper 30s. Patchy
frost can`t be ruled out the next few nights where surface
decoupling is most efficient.

On Friday, a more pronounced upper-level shortwave will drag a
pool of even cooler air into the region. With 850mb temperatures
of -5 to -6C, highs will stay decidedly in the 50s (upper 40s
lakeside). A diurnal flare to showers is expected once again,
perhaps with better coverage compared to today and Thursday
given cooler low-level temperatures (more diurnal instability).

Friday night continues to look like the chilliest night of the
pattern as a surface high pressure system shifts into the Great
Lakes allowing for surface winds to drop off and skies to clear.
The speed at which skies clear will be important to the
eventual overnight lows. With that said, current indications
are most areas should fall into the low to mid 30s. As a result,
we will continue to highlight Friday night/Saturday morning as
the period to watch for widespread frost.

This weekend, the aggregate upper-level troughing is expected
to shift eastward placing the Great Lakes in broad
northwesterly flow. At least some moderation in temperatures is
expected by early next week, though a parade of shortwaves will
lead to incrementally increasing chances for showers and perhaps
a few thunderstorms. Ensemble guidance favors the general
pattern of upper-level cyclonic flow in the northern United
States persisting into the second week of May, suggesting that
temperatures should remain seasonable (if not a hair below
average) until further notice.

Borchardt

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1223 PM CDT Wed Apr 29 2026

Key Messages:

- MVFR to Low VFR CIGs this afternoon.

- A few passing showers at the Chicago terminals this afternoon.

- North-northeast winds at the main Chicago terminals this
  afternoon, with prevailing northwesterly winds expected at DPA
  and RFD.

A lake breeze boundary will act as the focus for showers this
afternoon as a weather disturbance moves across the area. With
the chances looking to be the best near the boundary, we have
opted to add a tempo mention for showers at the main Chicago
terminals through early evening. Some MVFR CIGs will also
accompany the showers this afternoon.

While winds will primarily be north-northeasterly through the
remainder of the day at ORD, MDW and GYY, expect predominately
northwest winds at the inland terminals, at least through late
this afternoon. Tonight, winds will become light northerly before
settling northwesterly again on Thursday. There is also a small
chance (20-30%) that another lake breeze leads to an easterly
wind shift late Thursday afternoon. However, at this time we
have opted to forgo a formal mention in the ORD and MDW 30 hour
tafs. Otherwise, expect the possibility for additional scattered
showers Thursday afternoon.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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